Usage ^^^^^ snf-image-creator comes in 2 variants: * snf-image-creator: A non-interactive command line program * snf-mkimage: A user-friendly dialog-based program Both expect the input media as first argument. The input media may be a local file, a block device or *"/"* if you want to create an image out of the running system (see `host bundling operation`_). Non-interactive version ======================= snf-image-creator receives the following options: .. code-block:: console $ snf-image-creator --help Usage: snf-image-creator [options] Options: --version show program's version number and exit -h, --help show this help message and exit -o FILE, --outfile=FILE dump image to FILE -f, --force overwrite output files if they exist -s, --silent output only errors -u FILENAME, --upload=FILENAME upload the image to pithos with name FILENAME -r IMAGENAME, --register=IMAGENAME register the image with ~okeanos as IMAGENAME -a ACCOUNT, --account=ACCOUNT use this ACCOUNT when uploading/registering images [Default: None] -m KEY=VALUE, --metadata=KEY=VALUE add custom KEY=VALUE metadata to the image -t TOKEN, --token=TOKEN use this token when uploading/registering images [Default: None] --print-sysprep print the available enabled and disabled system preparation operations for this input media --enable-sysprep=SYSPREP run SYSPREP operation on the input media --disable-sysprep=SYSPREP prevent SYSPREP operation from running on the input media --no-sysprep don't perform any system preparation operation --no-shrink don't shrink the image --tmpdir=DIR create large temporary image files under DIR Most input options are self-describing. If you want to save a local copy of the image you create, provide a filename using the *-o* option. To upload the image to *pithos+*, provide valid credentials using *-a* and *-t* and a filename using *-u*. If you also want to register the image with *~okeanos*, in addition to *-u* provide a registration name using *-r*. By default, before extracting the image, snf-image-creator will perform a number of system preparation operations on the snapshot of the media and will shrink the last partition found. Both actions can be disabled by specifying *--no-sysprep* and *--no-shrink* respectively. If *--print-sysprep* is defined, the program will exit after printing a list of enabled and disabled system preparation operation applicable to this input media. The user can enable or disable specific *syspreps*, using *-{enable,disable}-sysprep* options. The user may specify those options multiple times. Running *snf-image-creator* with *--print-sysprep* on a raw file that hosts a debian system, we print the following output: .. _sysprep: .. code-block:: console $ snf-image-creator --print-sysprep debian_desktop.img snf-image-creator 0.1 ===================== Examining source media `debian_desktop.img'... looks like an image file Snapshotting media source... done Enabling recovery proc Launching helper VM... done Inspecting Operating System... found a(n) debian system Mounting the media read-only... done Enabled system preparation operations: cleanup-cache: Remove all regular files under /var/cache cleanup-log: Empty all files under /var/log cleanup-passwords: Remove all passwords and lock all user accounts cleanup-tmp: Remove all files under /tmp and /var/tmp cleanup-userdata: Delete sensitive userdata fix-acpid: Replace acpid powerdown action scripts to immediately shutdown the system without checking if a GUI is running. remove-persistent-net-rules: Remove udev rules that will keep network interface names persistent after hardware changes and reboots. Those rules will be created again the next time the image runs. remove-swap-entry: Remove swap entry from /etc/fstab. If swap is the last partition then the partition will be removed when shrinking is performed. If the swap partition is not the last partition in the disk or if you are not going to shrink the image you should probably disable this. use-persistent-block-device-names: Scan fstab & grub configuration files and replace all non-persistent device references with UUIDs. Disabled system preparation operations: cleanup-mail: Remove all files under /var/mail and /var/spool/mail remove-user-accounts: Remove all user accounts with id greater than 1000 cleaning up... If you want the image to have all normal user accounts and all mail files removed, you should use *--enable-sysprep* option like this: .. code-block:: console $ snf-image-creator --enable-sysprep cleanup-mail --enable-sysprep remove-user-accounts ... Dialog-based version ==================== *snf-mkimage* receives the following options: .. code-block:: console $ snf-mkimage --help Usage: snf-mkimage [options] [] Options: --version show program's version number and exit -h, --help show this help message and exit -l FILE, --logfile=FILE log all messages to FILE --tmpdir=DIR create large temporary image files under DIR If the input media is not specified in the command line, in the first dialog box the user will be asked to specify it: .. image:: /snapshots/select_media.png The user can select a file (regular or block device) or use the *Bundle Host* button to create an image out of the running system (see `Host bundling operation`_). After the input media is examined and the program is initialized, the user will be given the choice to run *snf-mkimage* in *wizard* or *expert* mode. Wizard mode ----------- When *snf-mkimage* runs in *wizard* mode, the user is just asked to provide the following basic information: * Name: A short name for the image (ex. "Slackware") * Description: An one-line description for the image (ex. "Slackware Linux 14.0 with KDE") * Account: An *~okeanos* account email * Token: A token corresponding to the account given above After confirming, the image will be extracted, uploaded to *pithos+* and registered with *~okeanos*. The user will also be given the choice to keep a local copy of it. For most users the functionality this mode provides should be sufficient. Expert mode ----------- Expert mode allows the user to have better control on the image creation process. The main menu can be seen in the picture below: .. image:: /snapshots/main_menu.png In the *Customize* sub-menu the user can control: * The system preparation operations that will be applied on the media * Whether the image will be shrunk or not * The properties associated with the image * The configuration tasks that will run during image deployment In the *Register* sub-menu the user can provide: * The credentials to login to *~okeanos* * A *pithos+* filename for the uploaded *diskdump* image * A name for the image to be registered to *~okeanos* with By choosing the *Extract* menu entry, the user can dump the image to the local file system. Finally, if the user selects *Reset*, the system will ignore all changes made so far and will start the image creation process again. Host bundling operation ======================= As a new feature in *v0.2*, snf-image-creator can create images out of the host system that runs the program. This is done either by specifying / as input media or by using the *Bundle Host* button in the media selection dialog of snf-mkimage. During this operation, the files of the disk are copied into a temporary image file, which means that the file system that will host the temporary image needs to have a lot of free space (see `large temporary files`_ for more information). Creating a new image ==================== Suppose you want to create a new Ubuntu server image. Download the installation disk from the Internet: .. code-block:: console $ wget http://ubuntureleases.tsl.gr/12.04.1/ubuntu-12.04.1-server-amd64.iso Verify that it has been downloaded correctly: .. code-block:: console $ echo 'a8c667e871f48f3a662f3fbf1c3ddb17 ubuntu-12.04.1-server-amd64.iso' > check.md5 $ md5sum -c check.md5 Create a 2G sparse file to host the new system: .. code-block:: console $ truncate -s 2G ubuntu_hd.raw And install the Ubuntu system on this file: .. code-block:: console $ sudo kvm -boot d -drive file=ubuntu_hd.raw,format=raw,cache=none,if=virtio \ -m 1G -cdrom ubuntu-12.04.1-server-amd64.iso .. warning:: During the installation, you will be asked about the partition scheme. Don't use LVM partitions. They are not supported by snf-image-creator. You will be able to boot your installed OS and make any changes you want (e.g. install openssh-server) using the following command:: $ sudo kvm -m 1G -boot c -drive file=ubuntu_hd.raw,format=raw,cache=none,if=virtio After you're done, you may use *snf-mkimage* as root to create and upload the image: .. code-block:: console $ sudo -s $ snf-mkimage ubuntu_hd.raw In the first screen you will be asked to choose if you want to run the program in *Wizard* or *Expert* mode. Choose *Wizard*. .. image:: /snapshots/01_wizard.png Then you will be asked to provide a name, a description, an *~okeanos* account and the token corresponding to this account. Finally, you'll be asked to confirm the provided data. .. image:: /snapshots/06_confirm.png Choosing *YES* will create and upload the image to your *~okeanos* account. Limitations =========== Supported operating systems --------------------------- *snf-image-creator* can only fully function on input media hosting *Linux* systems. The program will detect the needed metadata and you may use it to upload and register other *Unix* or *Windows* images, but you cannot use it to shrink them or perform system preparation operations. Logical Volumes --------------- The program cannot work on LVM partitions [#f1]_. The input media may only contain primary or logical partitions. Para-virtualized drivers ------------------------ *~Okeanos* uses the *VirtIO* framework. The disk I/O controller and the Ethernet cards on the VM instances are para-virtualized and need special *VirtIO* drivers. Those drivers are included in the Linux Kernel mainline since version 2.6.25 and are shipped with all the popular Linux distributions. The problem is that if the driver for the para-virtualized disk I/O controller is built as module, it needs to be preloaded using an initial ramdisk, otherwise the VM won't be able to boot. Many popular Linux distributions, like Ubuntu and Debian, will automatically create a generic initial ramdisk file that contains many different modules, including the VirtIO drivers. Others that target more experienced users, like Slackware, won't do that [#f2]_. *snf-image-creator* cannot resolve this kind of problems and it's left to the user to do so. Please refer to your distribution's documentation for more information on this. You can always check if a system can boot with para-virtualized disk controller by launching it with kvm using the *if=virtio* option (see the kvm command in the `Creating a new image`_ section). Some caveats on image creation ============================== Image partition schemes and shrinking ------------------------------------- When image shrinking is enabled, *snf-image-creator* will shrink the last partition on the disk. If this is a swap partition, it will remove it, save enough information to recreate it during image deployment and shrink the partition that lays just before that. This will make the image smaller which speeds up the deployment process. During image deployment, the last partition is enlarged to occupy the available space in the VM's hard disk and a swap partition is added at the end if a SWAP image property is present. Keep this in mind when creating images. It's always better to have your swap partition placed as the last partition on the disk and have your largest partition (*/* or */home*) just before that. Large temporary files --------------------- *snf-image-creator* may create large temporary files when running: * During image shrinking, the input media snapshot file may reach the size of the original media. * When bundling the host system, the temporary image file may became as large as the rest of the disk files altogether. */tmp* directory is not a good place for hosting large files. In many systems the contents of */tmp* are stored in volatile memory and the size they may occupy is limited. By default, *snf-image-creator* will use a heuristic approach to determine where to store large temporary files. It will examine the free space under */var/tmp*, the user's home directory and */mnt* and will pick the one with the most available space. The user may overwrite this behaviour and indicate a different directory using the *tmpdir* option. This option is supported by both *snf-image-creator* and *snf-mkimage*. .. rubric:: Footnotes .. [#f1] http://sourceware.org/lvm2/ .. [#f2] http://mirrors.slackware.com/slackware/slackware-14.0/README.initrd